It is sometimes necessary, by reason of injury or disease, to remove a portion of a vertebra from the spinal column. In such situations, a gap is left between adjacent vertebrae above and below the removed portion, which must be bridged or spanned structurally so that the vertical load on the spine can be transmitted safely across the gap. One technique used to accomplish this is bone fusion, which coheres the vertebrae as a monolithic element. A drawback of bone fusion, however, is that it requires a long period of recovery and rehabilitation. It is also known to use spinal stabilizing devices to separate the vertebra adjacent a damaged and/or partially removed vertebra. Some such devices, as shown, e.g., in U.S. Pat. Nos. 4,553,273 and 4,401,112, may be adjusted after insertion by means of a threaded shaft to provide a precise desired spacing. A drawback of spinal stabilizers has been the difficulty of placing and fixing them in the desired position, and the possibility that they might loosen or shift after they have been implanted in the body, by reasoning of turning of the threaded shaft.